Oxalate Molecule as the Trap for γ-Irradiation Energy in the Amorphous Aluminosilicate Al₂(OH)₆H₄SiO₄

Paramagnetic species which were the products of ? irradiation at 77 K and at room temperature were studied by ESR spectroscopy in the amorphous aluminosilicate, <tex-math>${\rm Al}_{2}({\rm OH})_{6}{\rm H}_{4}{\rm SiO}_{4}$</tex-math>, prepared in the presence and in the absence of oxalate ion. The aluminosilicate precipitated from the solution containing the oxalate ion in <tex-math>$10^{-4}\ {\rm mol}\ {\rm dm}^{-3}$</tex-math> concentration contained the oxalate only in trace amounts. When ?-irradiated at 77 K and at room temperature, this compound gave the stable paramagnetic species represented by the single ESR line centered at g = 2.000. We ascribe this spectrum to the CO₂^- radical formed from the oxalate ion. The same aluminosilicate prepared in the absence of the oxalate either produced no stable paramagnetic product after ? irradiation at room temperature or resulted in composite ESR spectra, indicating the presence of several paramagnetic species if irradiated at 77 K. Complex ESR spectra were transformed by heating to the stable paramagnetic centers which differed from the one obtained from oxlate ion. We conclude that in <tex-math>${\rm Al}_{2}({\rm OH})_{6}{\rm H}_{4}{\rm SiO}_{4}$</tex-math> oxalate acts as a trap for the ?-radiation energy.